A composition for ceramic substrates of interest to the present invention is described in, for example, Japanese Unexamined Patent Application Publication No. 2000-351668 (Patent Document 1). The composition for ceramic substrates is a mixture of borosilicate glass powder and ceramic powder, the borosilicate glass powder containing 5% to 17.5% by weight B2O3, 28% to 44% by weight SiO2, 0% to 20% by weight Al2O3, and 36% to 50% by weight MO (MO representing at least one selected from CaO, MgO, and BaO). The composition contains 40% to 49% by weight the borosilicate glass powder and 60% to 51% by weight the ceramic powder.
This composition for ceramic substrates, which can be sintered at low temperatures of 1000° C. or less, can be fired with a metal for making low-resistance metal-based conductor circuits, such as Ag- or Cu-based ones, in the production of a ceramic circuit component having such conductor circuits. Ceramic substrates containing this composition as a structural element, furthermore, offer high mechanical strength, a low dielectric constant, low loss, and a high thermal expansion coefficient which are all required of substrates, thereby providing ceramic circuit components such as multilayer ones having good characteristics and high reliability.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2000-351668